"A light is hung from rafter at a height h m above the floor , providing a circle of illumination. the illuminance E (in lumens/ squares meter or lm/`m^(2)` ) at ant point p on the floor varies...

"A light is hung from rafter at a height h m above the floor , providing a circle of illumination. the illuminance E (in lumens/ squares meter or lm/`m^(2)` ) at ant point p on the floor varies directly as the cosine of angle `theta` at which the rays leave the light source toward P, and inversely as the square of the height h of the light source, using k as the constant of variation, write expression for illuminance in term k, h, and `theta`. If the distance from the light source to point P is 13 m

write the expression in illuminance in terms of k and h alone.

for k = 15,600, what is the height of the light source, if E = 100lm/m^2?